Doctor blade assembly

ABSTRACT

A doctor blade assembly for holding a doctor blade which wipes excess ink from an etched or engraved ink applicator roll in a printing press enables the blade to be moved to a variety of positions with respect to the roll, imparts a reciprocating motion to the blade, enables skew adjustment of the blade, and clamps the blade in a convenient position to facilitate its replacement.

United States Patent Abler et a1.

[ Dec. 25, 1973 DOCTOR BLADE ASSEMBLY Inventors: Norman C. Abler, Milwaukee;

David R. l-lardt, Menomonee Falls, both of Wis.

Assignee: Faustel Incorporated, Butler, Wis.

Filed: Aug. 7, 1972 Appl. No.: 278,442

U.S. Cl. 101/363, 101/169 Int. Cl B411 31/04 Field of Search 101/157, 169, 350,

References Cited UNITED STATES PATENTS Paardecamp 101/157 Bamford 101/169 X Halley 101/169 2,676,539 4/1954 Behringer 101/157 3,017,828 l/l962 Behringer 101/169 UX 3,204,680 9/1965 Barry 151/69 3,361,059 l/1968 Klinger 101/169 3,521,561 7/1970 Pali et al.... 101/169 3,593,663 7/1971 Vischulis 101/157 Primary Examiner.l. Reed Fisher Att0rney-.1ames E. Nilles [57] ABSTRACT 4 Claims, 7 Drawing Figures PATENIED DECZS I975 smears PATENTEI] BEBZ 51975 SHEEI30F5 PATENTEB BEEZS I975 SHEEISBFS FIG. 7

DOCTOR BLADE ASSEMBLY BACKGROUND OF THE INVENTION 1. Field of Use This invention relates generally to adjustable doctor blade assemblies which hold doctor blades for wiping or scraping excess fluid from fluid application rolls of web processing machines.

2. Description of the Prior Art Some web processing machines, such as web type rotogravure and flexograph printing presses, employ an etched or engraved roll to which printing ink is applied by ink applicator means as the roll rotates. After application of the ink to the roll, a doctor blade mounted on a doctor blade assembly and in engagement with the roll surface wipes excess ink therefrom leaving ink only in the ink cells of the etched or engraved portions of the roll surface. After this, the roll either makes direct printing contact with the web being printed or makes contact with a rubber roll which then transfers ink to the web. This process is repeated for each rotation of the etched or engraved roll.

In some instances the doctor blade is mounted or supported on a doctor blade assembly which enables the blade to be moved to various positions with respect to the roll, which causes the blade to be moved reciprocably during operation to distribute blade wear evenly, and which permits replacement of the blade. A doctor blade assembly of this character is disclosed in U. S. Pat. No. 3,593,663 issued July 20, 1971 to Vischulis for Doctor Blade Assembly for Printing Equipment.

SUMMARY OF THE PRESENT INVENTION An improved doctor blade assembly in accordance with the present invention employes improved means or components arranged in an improved manner to enable the doctor blade to be moved to a wide variety of positions so as to accommodate etched or engraved rolls of various diameters used in the press and to enable the blade to be set at various appropriate angles with respect to a roll surface so as to accommodate roll rotation in either direction. The assembly also includes improved skew adjustment means for the blade, improved means for imparting reciprocating motion to the blade, and improved blade clamping means for the blade to rigidify it and to enable easy removal and replacement of a blade which exhibits wear.

A doctor blade assembly in accordance with the present invention is especially well-suited, for example, for use in flexograph presses wherein there are several upside and downside rolls which are closely arranged and wherein space is at a premium. However, the invention is usable in rotogravure and in other types of printing presses, as well as in other types of processing machines wherein a doctor blade and supporting assembly therefor is required to remove excess fluid from a roll surface.

Generally considered, a doctor blade assembly in accordance with the invention is mounted on a support frame on which or near which the roll to be doctored is rotatably mounted. A vertically movable or adjustable plate is mounted on the support frame and carries bearings on which the clamp frame shaft of a clamp frame is supported. The clamp frame is pivotably adjustable on these bearings and is also reciprocably movable axially on these hearings with respect to the plate. The clamp frame is reciprocated by means of a motor driven flexible cable (in a cable housing) which is attached to an anchor member on the clamp frame shaft. The cable housing is rigidly secured to the plate. The anchor member permits adjustable pivotal movement of the clamp frame. A clamp head is mounted for pivotal adjustable movement on the clamp frame. A clamp holder is provided on the clamp head and means are provided to effect skew adjustment movement of the clamp head with respect to the clamp frame. A twopiece blade clamp is releasably attached to the clamp holder and a doctor blade is releasably secured in the blade clamp.

Manually operable adjustment means or screws are provided to effect independent adjustment movement of the plate (vertical linear movement), the clamp frame (pivotal movement in a vertical plane), the clamp head (pivotal movement in a vertical plane), and the clamp holder (pivotal movement in a non-vertical plane). These movements allow the doctor blade to be moved to accommodate different sized rolls and to be placed in different locations and at different angles with respect to a particular roll, depending on direction of roll rotation and the nature of the engraving or etching on the roll surface.

The blade clamp and the clamp holder are constructed so that the means which secure the blade clamp to the clamp holder can be partially loosened or released manually to allow the blade clamp to be removed from the blade holder by a single man.

The blade clamp comprises two separable clamp portions between which the blade is clamped and which are releasable to allow removal of the blade.

, DRAWINGS FIG. 1 is a side elevational view in schematic form of a flexograph type printing press with a web therein and having a doctor blade assembly in accordance with the invention;

FIG. 2 is an enlarged side view of the doctor blade assembly shown in FIG. 1;

FIG. 3 is a front view of the doctor blade assembly taken on line 33 of FIG. 2;

FIG. 4 is a top view of the doctor blade assembly taken on line 44 of FIG. 2;

FIG. 5 is an isometric view showing details of the clamp holder and blade clamp shown in FIGS. 2 and 4;

FIG. 6 is an exploded view of the skew adjustment means shown in FIGS. 4 and 5; and

FIG. 7 is an end view of the skew adjustment means.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring to FIG. 1, the numeral 10 designates a flexograph type printing press in accordance with the invention having a web 11 to be printed therein which is understood to be movable in the direction of the arrow 12. In FIG. 1, the right side of press 10 is the downside and the left side is the upside. Press 10 is shown as having six printing stations, three downside and three upside. Up-side printing station 14 is typical of the two other up-side stations and is hereinafter described in detail.

Up-side station 114 comprises a steel backup roll 15 in contact with the rear unprinted side of web 11, a printing roll 16 preferably formed of rubber or the like for transferring an ink image to the front side of the web; and an engraved or etched metal roll 17 which transfers the ink image to printing roll 16. The rolls l5,

l6 and 17 are mounted on a support frame 20 of press for rotation in the direction of the arrows shown thereon in FIG. 1.

Station 14 also comprises an ink applicator means or assembly (not shown) to apply ink to the surface 22 of downside roll 17.

FIG. 1 further shows that station 14 comprises a doctor blade assembly 24 in accordance with the invention for removing excess ink from surface 22 of roll 17. FIG. 2 is an enlarged side view of doctor blade assembly 24 and FIGS. 3 and 4 are front and top views, respectively, taken on lines 3-3 and 44, respectively, of FIG. 2.

As FIGS. 2 and 3 show, doctor blade assembly 24 is mounted on support frame which comprises two spaced apart rigid side frames 26 and 27; with side frame 26 being visible in FIG. 2. Side frames 26 and 27 are interconnected and rigiditied by two tie bars 28 and 29, as shown in FIG. 2, which are welded thereto. Tie bar 28 has cutouts or recesses 31 on its surface.

Doctor blade assembly 24 comprises a plate which is slidably mounted for vertical movement between the side frames 26 and 27. Plate 30 is slidably supported between the recessed surface of tie bar 28 and two gibs or bars 32 and 33 which are rigidly secured as by welding to the side frames 26 and 27, respectively.

Referring to FIGS. 2 and 3, first means are provided for moving plate 30 vertically to a desired position by the press operator by rotation of a manually operable hand wheel 34 affixed to a shaft 35. Shaft 35 is supported at one end by a sleeve bearing 36 in a hole in side frame 26 and is supported at its other end by a sleeve bearing 37 in a support bracket 38 which is rigidly secured to tie bar 28. Shaft 35 is provided with a gear 40 which is in constant mesh with a gear 41 affixed to a shaft 42. Shaft 42 is supported at one end by a sleeve bearing 43 in a hole in support bracket 38 and is supported at its other end by a sleeve bearing 44 in a support bracket 45 which is rigidly secured to tie bar 28. The other end of shaft 42 is provided with a gear 46. The gears 41 and 46 on shaft 42 are in constant mesh with gears 50 and 51, respectively, which are secured to the lower ends of the vertically disposed rotatable threaded screw shafts 52 and 53, respectively. The screw shafts 52 and 53 are mounted near their lower ends for rotation on hearing blocks 54 and 55, respectively, which are rigidly secured to tie bar 28. The threaded upper end portions of the screw shafts 52 and 53 engage nuts 58 and 59, respectively, which are rigidly secured to vertically movable plate 30, as by bolts 60. Thus, rotation of shafts 35 and 42 in response to roration of hand wheel 34 ultimately effects rotation of the screw shafts 52 and 53 to cause vertical movement of plate 30.

Plate 30 is provided near its opposite ends with spaced apart brackets 62 and 63 which are secured thereto by bolts 64. The brackets 62 and 63 are provided with sleeve bearings 65 and 66, respectively, which support the ends of a clamp frame shaft 68 of a clamp frame 67. It is to be understood that shaft 68 is both rotatable to a limited degree and axially slidable in the bearings 65 and 66.

Second means are provided for effecting limited pivotal movement of clamp frame 67 with respect to plate 30. Shaft 68 of clamp frame 67 is rotatable by means of a manually rotatable clamp frame pivot screw 70, having an operators handle 71, which is supported for rotation on bearings 72 on a bracket 73. Bracket 73 is rigidly secured to plate 30 and is also supported on clamp frame shaft 68. Pivot screw is in constant mesh with clamp frame shaft gear 75 which is rigidly secured, as by a key 76, to clamp frame shaft 68 near one end thereof. Bracket 73, which is supported on clamp frame shaft 68, is rigidly secured to plate 30 as regards relative pivotal movement when screw 70 is turned to rotate gear '75 and shaft 68 by means of a roller bearing 73A on a shaft 73F on bracket 73 which is trapped between a rear bearing guide 73D on plate 30 and a front bearing guide 733 secured to plate 30, as by bolts 73C. Spacers 73E are provided on the bolts 73C between the guides 73B and 73D. Such an arrangement, of course, permits bracket 73 to move along with clamp frame 67 as the latter is moved axially.

Third means are provided for effecting reciprocating axial movement of clamp frame 67 with respect to plate 30. Shaft 68 is axially movable in an oscillating or reciprocating manner during press operation by means of a flexible cable 78 which is driven in a reciprocating manner with respect to its cable housing 79 by an eccentric drive means 80 on an electric motor 81. The end of cable housing 79 is secured by adjustable attachment means, including a threaded sleeve 82 and a nut 83, in a threaded opening 84 in bracket 63 on plate 30. The end of flexible cable 78 is secured by adjustable attachments means, including a threaded portion 85 and two nuts 86, in a threaded opening 87 in an anchor member 90. Anchor member 90 has a central opening in which a cylindrical bearing 91 is disposed for accommodating a portion 92 of shaft 68. It is to be understood that shaft 68 and portion 92 thereof are rotatable with respect to anchor member 90. Preferably, anchor member 90 is rigidly secured to plate 30 as regards relative pivotal movement when shaft 68 is rotated by means of a roller bearing 90A on anchor member 90 which is trapped between a rear bearing guide on plate 30 and on a front bearing guide 903 secured to plate 30, as by bolts 90C. Such an arrangement, of course, permits anchor member 96 to move reciprocably as it effects corresponding axial movement of shaft 68 of clamp frame 67. However, anchor member 90 is trapped against axial movement on portion 92 by an end sleeve 94 rigidly secured to portion 92 and by one side member 93 of clamp frame 67. During operation, reciprocating movement of cable 78 effects reciprocating movement of anchor member 90 and corresponding reciprocating movement of shaft 68 and clamp frame 67 thereon.

FIGS. 3 and 4 show that clamp frame 67 comprises two side members 93 and 96 which are rigidly mounted on and movable with shaft 68. The side members 93 and 96 afford support for a clamp head 97 which is mounted for limited pivotal or rotational movement on clamp frame 67. Clamp head 97 comprises a clamp holder portion (hereinafter referred to as a clamp holder) 110 which, in turn, supports a two-piece blade clamp 112 in which a doctor blade 113 is releasably mounted.

Fourth means are provided for effecting limited pivotal movement of clamp head 97 with respect to clamp frame 67. Clamp head 97 has a gear 100 rigidly secured thereon, as by a key 101, and gear 100 is in constant mesh with a clamp head pivot screw 102. Screw 102 is mounted for rotation on bearings 103 and 104 which are rigidly secured to side member 96 and screw 102 is rotatable by means of an operators handle 105.

Fifth means are provided for effecting skew adjustment movement clamp head 97 with respect to clamp frame 67 and comprise components hereinafter described in connection with FIGS. 4, 5, 6 and 7.

Sixth means are provided for releasably attaching a two-piece clamp 112 to clamp holder 110 and comprise a spring-loaded manually rotatable screw 117 which extends through an opening 1 19 in clamp holder 110 and takes into a threaded hole 121 in the lower portion 123 of the two-piece clamp l 12. Screw l 17 has a shoulder portion 118 which is engageable with clamp holder 1111 and a biasing spring 120 is disposed between shoulder 118 and clamp holder 110. Clamp 112 comprises two separable clamp portions 122 and 123 for engaging doctor blade 113 therebetween. As FIGS. 2, 4 and 5 show, upper portion 122 is secured to lower portion 123 by a plurality of removable bolts 130. Screw 117 serves as a releasable means for securing lower clamp portions 123 to clamp holder 110. Screw 117 is adjustable by tightening it down to rigidly secure clamp 112 to clamp holder 110. Screw 117 is further adjustable by loosening it to fully release clamp 112 from clamp holder 110. Spring 120 holds screw 117 clear of hole 121.

When it is desired to remove and replace blade 113, because of wear or other reasons, clamp holder 110 is rotated to a generally horizontal position wherein doctor blade 113 is disengaged from roll 17, as shown in phantom in FIG. 2. The screw 117 is then loosened to disengage it from clamp 112, whereupon clamp 112 can be slid out endwise from slot 125 or rotated upwardly to disengage it therefrom.

As FIGS. 2 and 5 show, clamp holder 110 has a tapered slot 125 therein and a projection 127 adjacent the slot. Lower clamp portion 123 has a clamp holder engaging portion 120 complementary in shape to slot 125. The other or upper clamp portion 122 is engageable or entrapped by projection 127.

Referring to FIGS. 4, 5, 6 and 7, the means for effecting skew adjusting movement of clamp head 97 with respect to clamp frame 67 are constructed as follows. One end of clamp head 97 has a short shaft 135 which is supported in a hole 136 in a skew hub 137. Skew hub 137 has a shaft 138 which is supported in a hole 139 in an adjusting hub 140. Adjusting hub 140 has a shaft 142 which is supported in a hole 141 in side member 93 of clamp frame 67. Skew hub 137 provided with tapped holes 150 by means of which it is rigidly secured to the end of clamp head 97. As FIG. 7 shows, shaft 138 of hub 137 is on a center line GL2. Shaft 142 of hub 140 is on another center line CLl which is displaced from centerline CL2. Therefore, relative rotational movement of hub 140 on hub 137 has the effect of shifting hub 137 (and the end of the clamp head 97 attached thereto) to the right or left with respect to side member 93 of clamp frame 67 in FIG. 7. Skew hub 137 is provided with two spaced apart ears or tabs 143 and 144 and the upper tab 143 is provided with a threaded hole 145 for receiving the threaded shaft of an adjusting screw 146. Screw 146 bears against an ear or tab 147 which is provided on adjusting hub 1411 and a compression type biasing spring 148 is disposed between tab 147 on adjusting hub 140 and lower tab 144 on skew hub 137. Adjusting movement of screw 146 causes relative rotational movement between the hubs 137 and and, because of the eccentricity of the two hubs, causes the left end (with respect to FIG. 4) of clamp head 97 to move toward or away from roll 17. Since blade 113 is ultimately supported on clamp head 97, skew adjusting movement of clamp head 97 effects corresponding movement of the blade.

I claim:

1. In a machine having a roll rotatably mounted thereon, and a doctor blade assembly having a doctor blade mounted for adjustable movement relative to the surface of said roll, said doctor blade assembly comprising: a support frame mounted adjacent said roll; a plate mounted for linear sliding movement on said support frame, first means connected to and between said support frame and said plate and selectively operable to move said plate linearly to desired positions with respect to said roll; spaced apart bearings mounted on said plate; a clamp frame comprising a clamp frame shaft mounted for axial and pivotal movement on said bearings and further comprising a pair of spaced apart side members mounted on and movable with said clamp frame shaft; second means connected to and between said plate and said clamp frame and selectively operable to move said clamp frame pivotally on said bearings; third means for reciprocably moving said clamp frame axially on said bearings, said third means comprising an anchor member mounted for relative rotational movement on said clamp frame shaft, a reciprocably movable cable connected to said anchor member, and drive means for effecting reciprocating movement of said cable, said anchor member and said clamp frame; a clamp head including a clamp holder portion mounted for pivotal movement between said pair of spaced apart side members of said clamp frame, said clamp holder portion having a clamp slot and a hole therein; fourth means connected to and between said clamp frame and said clamp head and selectively operable to pivotally move said clamp head; a blade clamp comprising two separable clamp portions for releasably engaging said doctor blade therebetween mounted on said clamp head, one of said clamp portions having a portion complimentary in shape to said clamp slot in said clamp holder portion of said clamp head and fitting therein, said one clamp portion having a threaded hole therein; connecting means for releasably connecting said blade clamp to said clamp head and comprising a threaded member extending through said hole in said clamp head and into releasable engagement with said threaded hole in said one clamp portion; and skew adjustment means connected to and between said one of said side members of said clamp frame and an end of said clamp head and selectively operable to effect skew adjusting movement of said clamp head with respect to said clamp frame.

2. A machine according to claim 1 wherein said skew adjustment means comprises a skew hub rigidly secured to said end of said clamp head, said skew hub having a skew hub shaft extending therefrom; an adjusting hub rotatably mounted on said one side member of said clamp frame and having a hole therein for receiving said skew hub shaft, said skew hub shaft and said hole in said adjusting shaft being relatively eccentrio with respect to each other; and means including an adjusting screw rotatably supported on said skew hub and in engagement with said adjusting hub to effect relative rotational movement between said hubs to cause said end of said clamp head to move relative to said clamp frame.

3. In a machine having a roll rotatably mounted thereon, and a doctor blade assembly having a doctor blade mounted for adjustable movement relative to the surface of said roll, said doctor blade assembly comprising: a support frame mounted adjacent said roll; a plate mounted for linear sliding movement on said support frame; first means connected to and between said support frame and said plate and selectively operable to move said plate linearly to desired positions with respect to said roll; spaced apart bearings mounted on said plate; a clamp frame comprising a clamp frame shaft mounted for axial and pivotal movement on said bearings and further comprising a pair of spaced apart side members mounted on and movable with said clamp frame shaft; second means connected to and between said plate and said clamp frame and selectively operable to move said clamp frame pivotally on said bearings, third means for reciprocably moving said clamp frame axially on said bearings, said third means comprising an anchor member mounted for relative rotational movement on said clamp frame shaft, a reciprocably movable cable connected to said anchor member, and drive means for effecting reciprocating movement of said cable, said anchor member and said clamp frame; a clamp head including a clamp holder portion mounted for pivotal movement on said clamp frame, said clamp holder portion having a clamp slot and a hole therein; fourth means connected to and between said clamp frame and said clamp head and selectively operable to pivotally move said clamp head; a blade clamp comprising separable upper and lower clamp portions for releasably engaging said doctor blade therebetween mounted on said clamp head, said lower clamp portion having a portion complimentary in shape to said clamp slot in said clamp holder portion of said clamp head and fitting therein, said one clamp portion having a threaded hole therein; connecting means for releasably connecting said blade clamp to said clamp head and comprising a threaded member extending through said hole in said clamp head and into releasable engagement with said threaded hole in said lower clamp portion, said connecting means further comprising a biasing spring between said threaded member and said clamp head to maintain said threaded member clear of said threaded hole when said threaded member is unscrewed therefrom so that said blade clamp can be removed from said slot; and skew adjustment means connected to and between said one of said side members of said clamp frame and said clamp head and selectively operable to effect skew adjusting movement of said clamp head with respect to said clamp frame, said skew adjustment means comprising a skew hub rigidly connected to said end of said clamp head and an adjusting hub rotatably connected to said one side member of said clamp frame, said skew hub having a skew shaft extending therefrom and said adjusting hub having a hole therein for receiving said skew hub shaft, said skew hub shaft and said hole in said adjusting hub being relatively eccentric with respect to each other, and means including an adjusting screw rotatably supported on said skew hub and in engagement with said adjusting hub to effect relative rotational movement between said hubs and thereby effect relative skew adjusting movement of said clamp head with respect to said clamp frame as the hubs are rotated with respect to each other.

4. A machine according to claim 3 wherein said skew hub comprises a pair of spaced apart projecting tabs thereon, one of said tabs having a threaded hole therein, and wherein said adjusting hub comprises a projecting tab thereon which is disposed between said pair of tabs on said skew hub, and wherein said adjusting screw is in threaded engagement with said threaded hole in said one tab of said pair of tabs and is in engagement with said tab on said adjusting hub, and including a compression spring disposed between the tab on said adjusting hub and the other tab of said pair of tabs on said skew hub. 

1. In a machine having a roll rotatably mounted thereon, and a doctor blade assembly having a doctor blade mounted for adjustable movement relative to the surface of said roll, said doctor blade assembly comprising: a support frame mounted adjacent said roll; a plate mounted for linear sliding movement on said support frame, first means connected to and between said support frame and said plate and selectively operable to move said plate linearly to desired positions with respect to said roll; spaced apart bearings mounted on said plate; a clamp frame comprising a clamp frame shaft mounted for axial and pivotal movement on said bearings and further comprising a pair of spaced apart side members mounted on and movable with said clamp frame shaft; second means connected to and between said plate and said clamp frame and selectively operable to move said clamp frame pivotally on said bearings; third means for reciprocably moving said clamp frame axially on said bearings, said third means comprising an anchor member mounted for relative rotational movement on said clamp frame shaft, a reciprocably movable cable connected to said anchor member, and drive means for effecting reciprocating movement of said cable, said anchor member and said clamp frame; a clamp head including a clamp holder portion mounted for pivotal movement between said pair of spaced apart side members of said clamp frame, said clamp holder portion having a clamp slot and a hole therein; fourth means connected to and between said clamp frame and said clamp head and selectively operable to pivotally move said clamp head; a blade clamp comprising two separable clamp portions for releasably engaging said doctor blade therebetween mounted on said clamp head, one of said clamp portions having a portion complimentary in shape to said clamp slot in said clamp holder portion of said clamp head and fitting therein, said one clamp portion having a threaded hole therein; connecting means for releasably connecting said blade clamp to said clamp head and comprising a threaded member extending through said hole in said clamp head and into releasable engagement with said threaded hole in said one clamp portion; and skew adjustment means connected to and between said one of said side members of said clamp frame and an end of said clamp head and selectively operable to effect skew adjusting movement of said clamp head with respect to said clamp frame.
 2. A machine according to claim 1 wherein said skew adjustment means comprises a skew hub rigidly secured to said end of said clamp head, said skew hub having a skew hub shaft extending therefrom; an adjusting hub rotatably mounted on said one side member of said clamp frame and having a hole therein for receiving said skew hub shaft, said skew hub shaft and said hole in said adjusting shaft being relatively eccentric with respect to each other; and means including an adjusting screw rotatably supported on said skew hub and in engagement with said adjusting hub to effect relative rotational movement between said hubs to cause said end of said clamp head to move relative to said clamp frame.
 3. In a machine having a roll rotatably mounted thereon, and a doctor blade assembly having a doctor blade mounted for adjustable movement relative to the surface of said roll, said doctor blade assembly comprising: a support frame mounted adjacent said roll; a plate mounted for linear sliding movement on said support frame; first means connected to and between said support frame and said plate and selectively operable to move said plate linearly to desired positions with respect to said roll; spaced apart bearings mounted on said plate; a clamp frame comprising a clamp frame shaft mounted for axial and pivotal movement on said bearings and further comprising a pair of spaced apart side members mounted on and movable with said clamp frame shaft; second means connected to and between said plate and said clamp frame and selectively operable to move said clamp frame pivotally on said bearings, third means for reciprocably moving said clamp frame axially on said bearings, said third means comprising an anchor member mounted for relative rotational movement on said clamp frame shaft, a reciprocably movable cable connected to said anchor member, and drive means for effecting reciprocating movement of said cable, said anchor member and said clamp frame; a clamp head including a clamp holder portion mounted for pivotal movement on said clamp frame, said clamp holder portion having a clamp slot and a hole therein; fourth means connected to and between said clamp frame and said clamp head and selectively operable to pivotally move said clamp head; a blade clamp comprising separable upper and lower clamp portions for releasably engaging said doctor blade therebetween mounted on said clamp head, said lower clamp portion having a portion complimentary in shape to said clamp slot in said clamp holder portion of said clamp head and fitting therein, said one clamp portion having a threaded hole therein; connecting means for releasably connecting said blade clamp to said clamp head and comprising a threaded member extending through said hole in said clamp head and into releasable engagement with said threaded hole in said lower clamp portion, said connecting means further comprising a biasing spring between said threaded member and said clamp head to maintain said threaded member clear of said threaded hole when said threaded member is unscrewed therefrom so that said blade clamp can be removed from said slot; and skew adjustment means connected to and between said one of said side members of said clamp frame and said clamp head and selectively operable to effect skew adjusting movement of said clamp head with reSpect to said clamp frame, said skew adjustment means comprising a skew hub rigidly connected to said end of said clamp head and an adjusting hub rotatably connected to said one side member of said clamp frame, said skew hub having a skew shaft extending therefrom and said adjusting hub having a hole therein for receiving said skew hub shaft, said skew hub shaft and said hole in said adjusting hub being relatively eccentric with respect to each other, and means including an adjusting screw rotatably supported on said skew hub and in engagement with said adjusting hub to effect relative rotational movement between said hubs and thereby effect relative skew adjusting movement of said clamp head with respect to said clamp frame as the hubs are rotated with respect to each other.
 4. A machine according to claim 3 wherein said skew hub comprises a pair of spaced apart projecting tabs thereon, one of said tabs having a threaded hole therein, and wherein said adjusting hub comprises a projecting tab thereon which is disposed between said pair of tabs on said skew hub, and wherein said adjusting screw is in threaded engagement with said threaded hole in said one tab of said pair of tabs and is in engagement with said tab on said adjusting hub, and including a compression spring disposed between the tab on said adjusting hub and the other tab of said pair of tabs on said skew hub. 